Natural Fiber Composites Research Articles

Thermo-physical and Fire Properties of Natural Fiber Composites for Energy Saving Applications

ABSTRACT Natural fiber composites are used in place of conventional materials for engineering applications due to their demand and imposed stringent government regulations across the globe. Thermo-physical properties are important in the selection of materials for energy saving applications. The objective of this research is to investigate the thermo-physical and fire properties of composites. In this study, vakka, elephant grass, and borassus fruit fibers are incorporated as reinforcement in the preparation of polymer composites. Thermal conductivity and specific heat of these composites were investigated experimentally by a guarded heat flow meter and differential scanning calorimeter. This investigation reveals that the thermal conductivity of composites decreased with the increase of fiber content and the quite opposite trend was observed with increase of temperature. At the maximum volume fraction of fiber, thermal conductivity of vakka fiber composite is lowest (0.179 W/mK) compared to other composites. The peak heat release rate and the flame retardant index are measured using Cone calorimeter and their values for vakka fiber reinforced composite is 373.45 kW/m2 and 1.5. Among all the composites, the vakka composite is suitable for energy saving and fire safety applications. The composites developed in this study could replace petroleum-based insulation materials.

Natural Fiber Composites from Coconut Fiber, Wood Powder, and Shellfish Shell of Centrifugal Clutch Materials

Natural fiber materials are the sustainable sources used for future automotive elements, where the centrifugal clutch utilizes the frictional force on the clutch pads to transfer kinetic energy from the rotating crankshaft to the transmission and the wheels. These pads are produced from several natural composites, such as coconut fiber, as well as wood and shellfish powder, whose characteristics are being investigated for hardness, microstructure, and wear properties. Based on this study, performance analysis was carried out on the samples of composite centrifugal clutch applied to automatic motorcycles. As a comparison, subsequent analysis was conducted on the genuine clutch pad materials, where the results showed differences in the characteristics of each mixture composition of the natural fiber composites. This indicated that the addition of wood powder composition to the clutch pad increased the hardness and special wear values by an average of approximately 12.9 and 1.16%, respectively. Furthermore, the composite content was observed in the microstructure, as the maximum power and torque on the natural fiber materials were 10.7 hp and 17.17 N.m, respectively. The value was found to be closely similar to the genuine parts with maximum power and torque of 10.8 hp and 16.02 N.m, respectively.

A Review of Natural Fibers Reinforced Composites for Railroad Applications

Composite materials are abundantly present in applications related to transportation industries, mainly due to their lightweight, good mechanical performance, and viable production costs. In this sector, weight reduction represents a two-fold advantage as fuel consumption can be reduced, as well as passenger (or load) capacity can be enhanced. The use of natural fiber composites is an excellent option considering weight reduction and source renewability, already being done in many automotive and aerospace utilities, but specifically in railroad applications, their choice seems to be eclipsed by synthetic fibers, such as glass and carbon fibers. The objective of this work is to analyze the current situation on composite applications in the railroad industry, deriving a discussion that includes the aspects that hinder the use of natural fibers and also indicates the current status of greener composites even if not including natural fibers. The production costs of these natural fiberreinforced composites, when observed under a scalability scenario, associated with some specific properties of natural fibers (as flammability performance, for example) seem to be the reason for their rather infrequent consideration. Nevertheless, technology advancements related to production processes and innovative additives fabrication present an interesting prospect for future development in agreement with sustainability concerns.

Mechanical, morphological and thermal analysis of unidirectional fabricated sisal/flax hybrid natural fiber composites

We report the spectroscopic, thermal, and mechanical outcomes of epoxy reinforced sisal/flax (S/F) hybrid natural fiber composites. This work is intended to enhance the mechanical and thermal properties of the sisal fibers in addition to flax fibers. In recent years, natural fiber composites gained inclusive credit as a supernumerary to conventional synthetic composites for their superior ecological properties. Five different varieties of composite slabs i.e., 60% epoxy matrix and 40% of sisal/flax fibers were fabricated unidirectionally through a simple hand layout method by varying sisal and flax ratio as (40/0, 30/10, 20/20, 10/30, and 0/40) with a constant weight fraction as 0.4Wf. The x-ray diffraction analysis was performed on the 20 S/20 F specimen and the crystallinity index is calculated as 42.84%. The spectroscopic and thermal studies were conducted on the 20 S/20 F sample and the chemical imprint of the composite is revealed by the strong peaks of cellulose, hemicellulose, and lignin along with amorphous and crystalline content of the FTIR data and is confirmed through the XRD data. The addition of flax fibers to sisal fibers showed a constructive improvement of thermal stability which is shown by the TG/DTA graph. In a three-stage degradation of sample, a maximum is observed at 334 °C. The tensile, flexural, and impact tests of all the fabricated composite samples are performed and ultimate tensile strength of 165.2 N/mm2 for the 40 S/0 F composite with an elongation of 9.2% is noted. The ultimate flexural stress of 8.1 N mm−2 is observed in composite 10 S/30 F and composite 10 S/30 F has an excellent ability to absorb impact force of 1.2 J energy. Based on the above results the manufactured composites exhibited higher thermal and mechanical properties showing a unique characteristic for different concentrations of flax fibers. Thus, the developed composites can be used individually for various applications based on the requirement of the end-user.

Experimental investigation of the effect of weave type on the mechanical properties of woven hemp fabric/epoxy composites

Natural fiber composites have a growing popularity as alternative materials to petroleum-based plastics and glass fiber reinforced composites due to various economic and environmental reasons. Textile preforms such as woven, knitted, braided, nonwoven, and multiaxial fabrics are commonly used in composite industry due to their high mechanical properties, tailorability, ease of handling during production, and versatility in material design. A range of properties can be obtained by varying the weave pattern and fabric architecture in woven fabric composites. In this study, epoxy composites reinforced with hemp woven fabrics with four different weave types were produced. The weave types chosen were quasi-unidirectional (UD), plain, basket 2/2, and twill 2/2 which are commonly used in the composite industry. Fabric properties such as yarn angle, yarn density, and crimp ratio were determined to evaluate their possible effect on composite properties. Tensile and three-point flexural tests were conducted in order to determine the effect of weave type on the mechanical properties of the resulting composites. It was found that UD composites show the highest tensile strength, tensile modulus, flexural strength, and flexural modulus in the 0° (yarn) direction. Plain weave fabric composites showed the second highest tensile and flexural strength and moduli followed by basket 2/2 weave composites. Composites reinforced with twill 2/2 woven fabrics showed the lowest mechanical properties due to high yarn crimp and yarn angle, less balanced structure, and resulting shear forces involved during various loading conditions.

Influence of extraction methods on mechanical, absorption and morphological properties of water hyacinth (Eichhornia crassipes) natural fibre composites: Environmental threat to successive commercial products

The goal of this research is to identify different types of water hyacinth plant fibre extraction methods, and what effect each of those methods has on mechanical, absorption and morphological properties of water hyacinth fibre composites. The main objective of this study was to identify some new extraction techniques to efficiently remove the aquatic waste of water hyacinth plants, and convert this biological waste into some successful commercial products. The first method of extraction in our study was the conventional retting method, followed by a manual extraction method, a hot water extraction method and a chemical hot water boiling method. The extraction process is then carried out with the help of an automated machine using a bare motor. The aim of this project is to increase the mechanical strength of hyacinth fibre by producing large quantities of fibre and by finding an optimal fibre extraction process. In the process of compression moulding, the fibres obtained from different extraction methods are combined with an epoxy matrix material to produce polymer composite samples. The mechanical strength, hardness and surface morphologies of the differently extracted water hyacinth fibre-reinforced composite samples are analysed in this work.

Natural-Fiber-Reinforced Chitosan, Chitosan Blends and Their Nanocomposites for Various Advanced Applications.

There has been much effort to provide eco-friendly and biodegradable materials for the next generation of composite products owing to global environmental concerns and increased awareness of renewable green resources. This review article uniquely highlights the use of green composites from natural fiber, particularly with regard to the development and characterization of chitosan, natural-fiber-reinforced chitosan biopolymer, chitosan blends, and chitosan nanocomposites. Natural fiber composites have a number of advantages such as durability, low cost, low weight, high specific strength, non-abrasiveness, equitably good mechanical properties, environmental friendliness, and biodegradability. Findings revealed that chitosan is a natural fiber that falls to the animal fiber category. As it has a biomaterial form, chitosan can be presented as hydrogels, sponges, film, and porous membrane. There are different processing methods in the preparation of chitosan composites such as solution and solvent casting, dipping and spray coating, freeze casting and drying, layer-by-layer preparation, and extrusion. It was also reported that the developed chitosan-based composites possess high thermal stability, as well as good chemical and physical properties. In these regards, chitosan-based “green” composites have wide applicability and potential in the industry of biomedicine, cosmetology, papermaking, wastewater treatment, agriculture, and pharmaceuticals.

Effect of reinforcements in chip forming mechanisms of discontinuous natural fiber composites while milling

Machining discontinuous natural fiber-reinforced composites (NFRCs) has been vitally challenging, mainly because of surface quality issues. Therefore, for the first time, an investigation to gain the phenomenological perspective of fundamental material removal mechanisms has been undertaken for two remarkably distinct polypropylene (PP) composites reinforced by rice husk (RH) and kenaf. In-situ side-end milling experiments have been performed employing a high-speed camera at different cutting speeds. The morphology of chip roots attained by a quick stop procedure along with chips is examined by scanning electron microscopy. The paper analyzes the distinct critical transitions in cutting mechanisms and cracking patterns along with chip reduction coefficients (ζ), shear angles (Ø), tool-chip temperatures, and friction coefficients (μ) influenced by the diverse reinforcement characteristics and cutting conditions. At low speeds, compared to kenaf/PP composites, RH/PP being less ductile with harder, more abrasive and larger width RH revealed reasonably defective slot side-wall surface, characterized by a cut through and dislodgement of RH.

Assessment on the Potential Application of Salago Fiber Composite as an Alternative Material in Drone Airframe

The capabilities of drones to perform dangerous missions have led to their development in various applications in different fields. Aside from the electronic components, an important part to be considered in their design is the airframe. It serves as the main structure that holds and supports the major components of a drone. In this research work, the potential use of salago fiber composite as an alternative airframe material has been assessed. The properties of this natural fiber composite have been compared to glass fiber composite such as density, heat deflection temperature, thermal behavior and mechanical strength. Although, the glass fiber composite remains superior in terms of flexural and impact strengths, the salago fiber composite still obtained a lower density (4.8 %) of 1.19 g/cm3 and a higher heat deflection temperature (7.9 %) of 58.6 °C. Moreover, the drone with an airframe made from salago fiber composite was able to fly successfully. Furthermore, the airframe was able to protect the components from damage after dropping the drone in a 2-meter height five times. Overall, the composite can be considered as an alternative material in drone airframes.

Machine learning approaches for prediction of properties of natural fiber composites : Apriori algorithm

ABSTRACT The selection of materials with the required properties was developing rapidly. There is no single rule to choose suitable material for a particular product. The complexes interrelation among the properties of composites makes more difficult to suggest suitable material for material scientist. The forecasting of relationship among material properties with throughput screening methods can help for the discovery of novel materials. The conventional way of selection of material need more investigations and time consuming. Recently, machine learning approaches are widely used in mechanical domain. Hence in this work, machine learning-based method was proposed to discover the relationship between the properties of natural fibres composites. To apply machine learning approach, there are 26 different natural fibres composites of Coir, Jute, Banana etc. were taken in to consideration. These materials are reinforced with pure export with different manufacturing methods such as Hand layup, Spray layup, Hot press moulding, and Compression moulding to produce the samples as per ASTM standards. The properties like density, tensile strength, hardness etc. were measured and interrelation among them was recognised using proposed method.

Uncertainty analysis of mechanical behavior of natural fiber composites

The natural origin of the fibers combined with random production flaws results in significant uncertainties in the properties of natural fiber-reinforced composites. A probabilistic assessment can help to characterize the uncertainties and evaluate the reliability of natural fiber composites, enabling their use in engineering designs. To this end, this study aims to analyze the uncertainties in the tensile strength and frequency response of a unidirectional flax/epoxy composite due to the actual variability of various input parameters, including the fiber material properties and manufacturing flaws. Based on the available data in the literature, the non-deterministic input variables were divided into normal and uniform variables using a statistical test. A computationally efficient response surface approach based on the polynomial chaos expansion was proposed to conduct the uncertainty analysis with multi-type uncertain variables. Moreover, the results were validated by experimental measurements and compared with the direct Monte Carlo simulation to demonstrate the accuracy and efficiency of the surrogate model.

Effect of basalt intraply hybridization on the damage tolerance of flax laminates: Experimental analysis and analytical modeling under low-velocity impact

Since natural fiber composites have a high potential as an alternative to synthetic materials, their mechanical properties must be investigated under different loading modes. In this paper, flax, basalt and hybrid flax-basalt/epoxy resin composite laminates are experimentally characterized and their behavior under low-velocity impact conditions is investigated. Analytical models, on their part, represent a low-cost and low-time consuming tool to provide initial considerations on the mechanical behavior of these relatively new composites in load-bearing applications. Therefore, in this work, analytical models previously introduced for synthetic fiber laminates are used to provide an approximation of the load–displacement curve resulting from a low-velocity impact on flax, basalt and flax/basalt hybrid laminates. In particular, an attempt is made to predict the descending phase of the load–displacement curve. To validate the theoretical results, an experimental campaign was carried out with different impact energies from 2.5 J to 10 J at room temperature. The experimental results showed a significant improvement in the quasi-static mechanical properties and damage tolerance of the hybrid composites compared to flax-based laminates. The analytical results confirmed that the presented models are well able to predict the response of natural fiber composites during loading and unloading phases for all considered material configurations.

The effect of various composite and operating parameters in wear properties of epoxy-based natural fiber composites

The effect of various composite and operating parameters in wear properties of epoxy-based natural fiber composites

Resin Transfer Molding of Wood Strand Composite Panels

The purpose of this study was to develop high-performance wood strand panels for automotive application using resin transfer and compression resin transfer molding technologies. Wood strand preforms bonded with 1%, 5%, and 20% by weight low-density polyethylene and 1% by weight high-density polyethylene were impregnated with resin during the molding process and compared. The results showed that 1% low-density polyethylene is sufficient to bind wood strands into a stable preform for handling and processing. Permeability measurements using a volumetric interpretation of Darcy’s law accounted for resin flow through the thickness of the preform. When compared with previously published data on other natural fiber composites, resin transfer molded wood strand composites generally exhibited superior mechanical properties and significantly greater dimensional stability when exposed to moisture.

Biocarbon: A lightweight, functional filler for under‐the‐hood automotive composites

AbstractIn recent years, automotive manufacturers have increased their use of natural fiber composites to reduce vehicle weight and improve carbon footprint. However, natural fibers have lower thermal stability than many synthetic fiber alternatives, limiting their application to low‐processing temperature polymers and low‐temperature automotive environments. Pyrolysis of biomass yields a porous substance called biocarbon, which has superior thermal performance and hydrophobicity than biomass. This study evaluated the effects of biocarbon pyrolysis conditions and biomass source on the properties of biocarbon powders and the performance of biocarbon as a reinforcing agent in thermoplastic composites. Hybrid biocarbon‐glass fiber polyamide‐6 composites were generated with varying loading level and biocarbon type. Composites were evaluated in terms of mechanical (tensile and impact), morphological (scanning electron microscope), and thermal performance (thermal gravimetric analysis [TGA] and differential scanning calorimetry [DSC]); the chemical characteristics (X‐ray photoelectron spectroscopy and Fourier transform infrared) and thermal performance (TGA and DSC) of biocarbon powders were also determined. A 10% increase in the loading level of biocarbon resulted in a 7%–10% improvement in composite strength. Biomass source affected the thermal stability of a biocarbon powder. Coconut‐based biocarbon composites exhibited thermal performance comparable to materials currently used in automotive fan‐and‐shroud applications, suggesting that biocarbon composites have the potential for use as low‐density, high‐temperature automotive materials.

Study on characterization of water hyacinth (Eichhornia crassipes) novel natural fiber as reinforcement with epoxy polymer matrix material for lightweight applications

In this study, the primary goal is to utilize the biological waste of water hyacinth (Eihhornia crassipes) plant fiber–reinforced polymer composite materials for commercial applications, especially for lightweight materials aspects. In this work, the physical, mechanical (tensile, flexural, and impact), thermal, and morphological properties of water hyacinth natural fiber composite samples are investigated. We strongly believe that only a minimum amount of work has to be done to this water hyacinth fiber composite oriented. Especially all the previous literature reported the hyacinth fibers are extracted from the retting process and manual method. But, in this work, hyacinth fibers are extracted from the new novel mechanical way of the extraction process. From the results of chemical analysis, water hyacinth fiber contains a very high 62.15% cellulose content and a minimum amount (14.82%) of hemicellulose content. The crystallinity index of water hyacinth fiber composite is 54.82%. The surface of the hyacinth composite is examined with the help of a scanning electron microscope. The thermal degradation of hyacinth fiber composite is measured with the help of the thermogravimetric analysis method. Based on the final experimental results, the water hyacinth natural fiber composite is the better alternative for other traditional fiber composites and it is strongly recommended for lightweight material applications.

Effect of process conditions on the filament diameter in single screw extrusion of natural fiber composite

Thermoplastic elastomer filaments, both unreinforced and reinforced with soyhull fibers, were extruded using a single screw extruder. Nozzle diameter, extrusion speed, and water bath distance were the process variables. Statistical analysis was performed to study the influence of process variables and predict the diameter of the extruded filament. Among experiment variables, the nozzle diameter affected most the outcomes of the resultant filament diameter, and the generated extruder pressure and torque. ANOVA also revealed the significant effect of all the process variables on the filament diameter. In addition, an ANN prediction model was developed which was effective in predicting the filament diameter, with a resulting R-squared value of 0.99 between target and output prediction.

A Study on the Effect of Fiber Volume Ratio on the Physical and Mechanical Properties of Natural Fiber Composites

Abstract: At present, natural fibers of renewable resources offer the potentiality to act like a reinforcing material for manufacturing of composites. This study provides the effect of fiber volume ratio on physical & mechanical properties of specimen when the fiber length is fixed and randomly oriented. For the fabrication of composite samples, the natural fiber was used as a reinforced material and adhesive material was Phenol-Formaldehyde. Fibers of hemp, coconut & jute are used in equal ratio for the research work. In this study the fiber length was fixed in all samples and the fibers were randomly orientated and the thickness of all samples was 5mm. The length of the fibers was 12mm. A total of four samples S1, S2, S3, and S4 were fabricated using hand lay-up method. Fiber volume ratio is varied from 30% to 60%, such as 30% in S1, 40%in S2, 50% in S3 & 60% in S4 sample. Physical & Mechanical Testing has been carried out as per standards on the prepared specimens. Water absorption test was carried out in two sets one for 2 hours & second for 24 hours. Result shows that fiber volume ratio of 40% in S2 showed maximum density, water absorption test was found minimum for 2 and 24 hours test & minimum moisture. At 30% fiber ratio (S1) the expansion in length, width, and thickness was found minimum during the dimension expansion test for 2 hour soaking. Modulus of elasticity of the composite was found maximum at 50% fiber ratio (S3) inside composite and modulus of rupture found maximum at 60% fiber ratio (S4). The study on the effect of fiber ratio on mechanical and physical properties has been done.

Deep learning segmentation of wood fiber bundles in fiberboards

Natural fiber composites and fiberboards are essential components of a sustainable economy, making use of bio-sourced, and also recycled materials. These composites’ structure is often complex, and their mechanical behavior is not yet fully understood. A major barrier in comprehending them is the ability to identify the fibers in situ, i.e. embedded in complex fibrous networks such as medium-density fiberboards (MDF). To that end, the first step is to separate individual wood fibers from fiber bundles. Modern material studies on real world, dense fibrous materials using X-ray microtomography and 3D image analysis were always limited in accuracy. However, recent machine learning techniques and particularly deep learning may help to overcome this challenge. In this work, we compare existing segmentation algorithms with the performance of convolutional neural networks (CNNs). We explain the need for network complexity, and demonstrate that our best algorithm, based on the UNet3D architecture, reaches unprecedented accuracy. Moreover, it achieves the first segmentation sufficiently qualitative to extract morphometric measurements of the fiber bundles and accurately estimate their density. Among other applications, the proposed method thus enables the design of more realistic material models of MDF, and is a milestone towards the understanding and improvement of this wood-based product.

Improved mechanical and water absorption properties of epoxy-bamboo long natural fibres composites by eco-friendly Na2CO3 treatment

ABSTRACT Epoxy-bamboo long natural fibres composites were prepared by hand lay-up method to study the influence of fibre’s treatment on their characteristics. SEM showed increased surface roughness due to the removal of amorphous compounds from the treated fibre as confirmed by the disappearance of certain peaks in FTIR spectroscopy. Resultantly, ∼52% increase in crystallinity was observed by XRD analysis. TGA results also showed the effectiveness of the treatment as mass loss for treated fibres was ∼15% lesser than the untreated fibres. Moreover, thermogravimetric analysis of composites showed highest mass loss in untreated fibres composites and lowest in neat epoxy. The DSC-DTA curves indicated an early start of initiation temperature in treated fibre composite. Tension tests showed ∼12% and ~16% increase in tensile strength and modulus respectively for treated fibres composite due to increased interfacial strength caused by fibre treatment. Treatment also resulted in decreased impact energy and water absorption level.